'\" te
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.TH DOOR_SERVER_CREATE 3C "May 12, 2017"
.SH NAME
door_server_create \- specify an alternative door server thread creation
function
.SH SYNOPSIS
.LP
.nf
\fBcc\fR \fB-mt\fR [ \fIflag\fR... ] \fIfile\fR... [ \fIlibrary\fR... ]
#include <door.h>

\fBvoid (*)(door_info_t *)\fR \fBdoor_server_create\fR(\fBvoid (*\fR\fIcreate_proc\fR)(door_info_t *));
.fi

.SH DESCRIPTION
.LP
Normally, the doors library creates new door server threads in response to
incoming concurrent door invocations automatically. There is no pre-defined
upper limit on the number of server threads that the system creates in
response to incoming invocations (1 server thread for each active door
invocation). These threads are created with the default thread stack size and
POSIX (see \fBstandards\fR(7)) threads cancellation disabled. The created
threads also have the \fBTHR_BOUND\fR | \fBTHR_DETACHED\fR attributes for
Solaris threads and the \fBPTHREAD_SCOPE_SYSTEM\fR |
\fBPTHREAD_CREATE_DETACHED\fR attributes for POSIX threads. The signal
disposition, and scheduling class of the newly created thread are inherited
from the calling thread (initially from the thread calling
\fBdoor_create()\fR, and subsequently from the current active door server
thread).
.sp
.LP
The \fBdoor_server_create()\fR function allows control over the creation of
server threads needed for door invocations. The procedure \fIcreate_proc\fR is
called every time the available server thread pool is depleted. In the case of
private server pools associated with a door (see the \fBDOOR_PRIVATE\fR
attribute in \fBdoor_create()\fR), information on which pool is depleted is
passed to the create function in the form of a \fBdoor_info_t\fR structure.
The \fBdi_proc\fR and \fBdi_data\fR members of the \fBdoor_info_t\fR structure
can be used as a door identifier associated with the depleted pool. The
\fIcreate_proc\fR procedure may limit the number of server threads created and
may also create server threads with appropriate attributes (stack size,
thread-specific data, POSIX thread cancellation, signal mask, scheduling
attributes, and so forth) for use with door invocations.
.sp
.LP
The overall amount of data and argument descriptors that can be sent through a
door is limited by both the server thread's stack size and by the parameters of
the door itself. See \fBdoor_setparam\fR(3C).
.sp
.LP
The specified server creation function should create user level threads using
\fBthr_create()\fR with the \fBTHR_BOUND\fR flag, or in the case of POSIX
threads, \fBpthread_create()\fR with the \fBPTHREAD_SCOPE_SYSTEM\fR attribute.
The server threads make themselves available for incoming door invocations on
this process by issuing a \fBdoor_return\fR(\fBNULL, 0, NULL, 0\fR). In this
case, the \fBdoor_return()\fR arguments are ignored. See \fBdoor_return\fR(3C)
and \fBthr_create\fR(3C).
.sp
.LP
The server threads created by default are enabled for POSIX thread
cancellations which may lead to unexpected thread terminations while holding
resources (such as locks) if the client aborts the associated
\fBdoor_call()\fR. See \fBdoor_call\fR(3C). Unless the server code is truly
interested in notifications of client aborts during a door invocation and is
prepared to handle such notifications using cancellation handlers, POSIX
thread cancellation should be disabled for server threads using
\fBpthread_setcancelstate\fR (\fBPTHREAD_CANCEL_DISABLE\fR, \fINULL\fR). If all
doors are created with the \fBDOOR_NO_CANCEL\fR flag (see
\fBdoor_create\fR(3C)), the threads will never be cancelled by an aborted
\fBdoor_call()\fR call
.sp
.LP
The \fIcreate_proc\fR procedure need not create any additional server threads
if there is at least one server thread currently active in the process (perhaps
handling another door invocation) or it may create as many as seen fit each
time it is called. If there are no available server threads during an incoming
door invocation, the associated \fBdoor_call()\fR blocks until a server thread
becomes available. The \fIcreate_proc\fR procedure must be MT-Safe.
.SH RETURN VALUES
.LP
Upon successful completion, \fBdoor_server_create()\fR returns a pointer to the
previous server creation function. This function has no failure mode (it cannot
fail).
.SH EXAMPLES
.LP
\fBExample 1 \fRCreating door server threads.
.sp
.LP
The following example creates door server threads with cancellation disabled
and an 8k stack instead of the default stack size:

.sp
.in +2
.nf
#include <door.h>
#include <pthread.h>
#include <thread.h>

void *
my_thread(void *arg)
{
        pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, NULL);
        door_return(NULL, 0, NULL, 0);
}
void
my_create(door_info_t *dip)
{
        thr_create(NULL, 8192, my_thread, NULL,
                   THR_BOUND | THR_DETACHED, NULL);
}
main(\|)
{
        (void)door_server_create(my_create);
        \|.\|.\|.
}
.fi
.in -2

.SH ATTRIBUTES
.LP
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Architecture	all
_
Interface Stability	Stable
_
MT-Level	Safe
.TE

.SH SEE ALSO
.LP
.BR door_bind (3C),
.BR door_call (3C),
.BR door_create (3C),
.BR door_return (3C),
.BR pthread_create (3C),
.BR pthread_setcancelstate (3C),
.BR thr_create (3C),
.BR attributes (7),
.BR cancellation (7),
.BR standards (7)
